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Engine Run in or Break in

HighSchoolBuilders

Well Known Member
Hi All,

I have a Titan IOX-360, I am not knowledgeable with piston engines and it has been a rather steep learning curve for me.

After reading the run in/break in instruction from ECi, I am still unsure where I need to break in the engine. The engine has been ran in the cell for 6.5 hours, according to the log, CHT dropped at around 4.5 hours. I am not sure what does that exactly means and what is next to follow. I have been researching online and get the impression I need to break in the engine next, but I also read that the engine with the time it spent at the test cell is equivalent to a proper break in and I can use the engine normally without the concerns related to break in/run in.

A quick background: We are the first in Hong Kong to register and fly a homebuilt aircraft. Being the first means a lot of restriction, one of them is at this stage, we are only allow to fly ONE traffic pattern with our aircraft. All engine run and test has to be done on the ground. I need to formulate a plan that would allow us to test and run and break the engine for our first and only flight, without damaging the engine permanently.

Would greatly appreciate if all of you engine gurus can shed some light for me. Thanks!
 
You will get lots of opinions, but mine is that this engine is essentially broken in. Flying one pattern is not going to hurt it.
Triple check all mechanical and fluid connections. Check the mag timing.
Do a brief ground run, then de-cowl and look for anything wrong - fuel or oil leaks, etc.
Then go fly.
 
Engine run and taxi test

Thanks Bob! How long was your engine run and taxi test? I need to formulate a plan and submit it to the government for approval. Is there any good material out there on what to test and check on each engine run and taxi test? So far, I based my plan on AC90-89, and Kevin Horton has the best material I can find online.
 
I am opposed to taxi testing. Not enough airspeed for cooling, limited time to operate at high power. I only did this once, and that was to condition the brake pads.
Basically you're 95% done once CHTs drop and oil consumption stabilizes.
 
Lycoming Instruction

http://www.lycoming.com/Portals/0/t...ating engine Break-In and Oil Consumption.pdf

The more I read the more I am confused. The Lycoming service instruction mention 15 mins of ground run at 1500rpm. This is against what I have been told to limit my ground run no more than 3-5 mins. My understanding so far is that heat is my main concern and the CHT is really what drives the length of the test, as long as I maintain the CHT below 350F.
 
As far as I'm concerned this is the definitive run-in/break-in schedule from Mahlon...

http://www.vansairforce.com/community/showpost.php?p=768808&postcount=6

Hope this helps!This is how I would do the initial runs. I have used this procedure thousands of times with complete success.
Good luck,
Mahlon

CYLINDER RUN-IN INSTRUCTIONS FOR CHANNEL CHROME,
CERMICROME, AND CERMINIL BARRELS

1] Install mineral oil in ALL normally aspirated engines and all Teledyne Continental turbocharged engines. Install AD oil in all Textron Lycoming turbo charged engines.

2] Start engine, run at 800 R.P.M.'s for three (3) minutes, shut down, check for leaks.

3] Start engine, run at 1,000 R.P.M.'s for three (3) minutes, shut down, check for leaks.

4] Cowl aircraft.

5] Start engine, run at 1,200 R.P.M.'s for three (3) minutes, shut down, park into wind.

6] Start engine, run at 1,400 R.P.M.'s for three (3) minutes, shut down, park into wind.

7] Start engine, run at 1,400 R.P.M.'s for five (5) minutes, run up to full power, check all engine parameters, retard power to 1,000 R.P.M. for one (1) minute, shut down.

8] Check for leaks The engine has now had it's Test Cell run time and is ready for other ground runs, taxi tests, adjustment runs, etc., observing the precautions from the post

All runs should be made into the wind.

At no time during these runs should CHT exceed 350F.

Between all engine runs, allow adequate cool off time.

Before proceeding to next run, you should be able to hold your hand on a rear cylinder head for three to five seconds.

CYLINDER RUN-IN FOR STEEL,
NITRIDED OR REBARRELED CYLINDERS

1] Install mineral oil in the engine.

2] Start engine, run at 800 R.P.M.'s for three (3) minutes, shut down, check for leaks.

3] Start engine, run at 1,000 R.P.M.'s for three (3) minutes, shut down, check for leaks.

4] Cowl aircraft.

5] Start engine, run at 1,200 R.P.M.'s for three (3) minutes, shut down, park into the wind.

6] Start engine, run at 1,400 R.P.M.'s for five (5) minutes, shut down, park into wind.

7] Start engine, run at 1,400 R.P.M.'s for ten minutes, shut down, park into wind.

8] Start engine, run at 1,400 R.P.M.'s for five (5) minutes, run up to full power, check all engine parameters, retard power to 1,000 R.P.M. for one (1) minute, shut down.

9] Check for leaks The engine has now had it's Test Cell run time and is ready for other ground runs, taxi tests, adjustment runs, etc., observing the precautions from the post

All runs should be made into the wind.

At no time during these runs should CHT exceed 350F.

Between all engine runs, allow adequate cool off time.

Before proceeding to next run, you should be able to hold your hand on a rear cylinder head for three to five seconds.

This is some information on running after completing the above schedule:
Knowing this crucial information allows us to make practical decisions regarding ground runs and flight profiles from the new or newly overhauled engine point of view.
To put it simply, if we get the ring to cylinder interface too hot from too hard of running, lack of cooling or another reason we will glaze the cylinder walls and prevent actual break in from occurring. Because, we are dealing with multiple independent cylinders on the engine, these conditions can happen to one cylinder, all cylinders or anything in between on the same engine. So our job above all other aspect of engine operation during the break in phase, is to keep the cylinder's as cool as possible. If we do this we will not have any problems or issues with the engine as far as break in goes. During any and all ground runs we should limit the duration and actual temps we encounter to prevent glazing from happening. We tell our customers to keep all ground runs less than 10 minutes. Don't run the engine above 2000 RPM unless you are doing a momentary full power check, high speed taxi tests or actual take off runs. If the CHT goes above 350*F or the oil temp goes above 180*F at any point during the 10 minute max. duration ground run, or at the expiration of the ten minute time limit, that run should be terminated. Then, park the aircraft faced into the wind and allow the engine to cool, until you can place your hand on the cylinder heads and barrels for 5 seconds without hurting or burning you hand and the cylinders feel relatively cool to the touch. After the engine has cooled, continue with the last run where you left off. Obviously, from what we have learned about temperature, running the engine more conservatively will not cause any problems and may even help the break in process but operating within these restrictions, on the ground, should prevent any glazing issues. These limitations apply to an engine that has had a test cell run before any ground runs are attempted. If your engine hasn't had any test cell time, then I can supply you with a ground run schedule, to replace the test cell run, which can be performed on the aircraft. If you want or need that information, just email me privately and I would be happy to send it along.
When it comes time to fly the aircraft, once again we want to observe the ground run rules, for taxi and warm up. Once we are ready to fly, we want to use full power for take off and initial climb and then we want to reduce power to climb power(normally around 85%) until we reach a safe altitude above the airport. Keep the climbs, as flat as possible, to maintain as much cooling as possible. Remember that heat is our major enemy and we can control that with climb speed. After establishing an appropriate altitude, reduce power to 65% to 75% ( preferably 75 % if speed restrictions will allow it). If we see temps, exceeding 15% of our ground run limitations, in initial flights, we should reduce power to control those temps and land the aircraft. Then, double check all cooling associated equipment, repair as necessary if you find a defect, let the engine cool off and fly it again, taking up from where you left off, observing the same restrictions. The first flight shouldn't be any longer than 10 or 15 minutes maximum, even with good cooling that would allow a longer flight. The first flight is a "test flight" and after landing you should do a through visual inspection of the engine and its installation, for leaks and any other operational issues like interference fits that showed up under power, chafing of lines etc. After the first flight issues are checked, we are ready for further flights under the same ground run and flight restriction's we have been observing. The key issue once again is heat. If we control the heat by power setting, airspeed, step climbing or any other means at our disposal we will not glaze the cylinders and we will successfully break the engine in. If we operate the engine at too low of a power setting, to seat the rings, we will not harm the engine or the eventual break in process, unless we develop enough heat to glaze the cylinders. In another words, operation at a low power setting, isn't a deterrent for break in unless we have the heat.
The rest of this article is in part II
 
Listen to what people's opinions are but follow the manual. This is especially true for temperature values. You will get lots of conflicting "opinions" but follow the manual. Besides, it is more convincing to a government official to quote a manufacturer's published manual than to quote somebody off the INTERNET.

My 2 cents.

:cool:
 
Last edited:
Hi All,

I have a Titan IOX-360, I am not knowledgeable with piston engines and it has been a rather steep learning curve for me.

After reading the run in/break in instruction from ECi, I am still unsure where I need to break in the engine. The engine has been ran in the cell for 6.5 hours, according to the log, CHT dropped at around 4.5 hours. I am not sure what does that exactly means and what is next to follow. Would greatly appreciate if all of you engine gurus can shed some light for me. Thanks!

The initial break in has already been accomplished by the 6.5 hours of run time in the test cell. Operate the engine normally. Pay close attention to CHTs during operation. If you do experiance high CHTs at this point in time it is most likely to cooling baffle/baffle seal installation, not new cylinder break in.
 
The more I read the more I am confused. The Lycoming service instruction mention 15 mins of ground run at 1500rpm. This is against what I have been told to limit my ground run no more than 3-5 mins. My understanding so far is that heat is my main concern and the CHT is really what drives the length of the test, as long as I maintain the CHT below 350F.

Listen to Mike Hammond. You are confusing a no-test-cell break-in procedure with a test-cell break in. Your engine is 95% broken-in from the test cell. The CHT drop logged at 4.5 hours in the test cell is the new cylinders honed surfaces being worn-in and properly holding an oil film that reduces friction and thus reduces CHT. That engine is ready to takeoff and be run at full power.

350F is very conservative. Lycoming says keep CHTs below 400F "for longest service life" but the max is 500F.
 
The initial break in has already been accomplished by the 6.5 hours of run time in the test cell. Operate the engine normally. Pay close attention to CHTs during operation. If you do experiance high CHTs at this point in time it is most likely to cooling baffle/baffle seal installation, not new cylinder break in.

I missed that part and agree. Your engine has been run-in. You just need to run it once to make sure you have no leaks or operational issues and then fly it.
 
Sounds good

That sounds good and what I am hoping to hear. Having said that, I shouldn't let the engine ever get above 400F, even though the engine has been broken in, right?
 
That sounds good and what I am hoping to hear. Having said that, I shouldn't let the engine ever get above 400F, even though the engine has been broken in, right?

Lycoming says keep CHTs below 400F "for longest service life" but the max is 500F.

Once again, follow what the manual states. As a GENERAL rule: 400F max for continuous economy cruise. 435 high performance cruise. Max is 500F.

Lycoming O-360 and Associated models

:cool:
 
That sounds good and what I am hoping to hear. Having said that, I shouldn't let the engine ever get above 400F, even though the engine has been broken in, right?

It will not harm your engine to go above 400F. Climbing-out and testing a new engine, one will often see the low 400s until the baffling is sorted out and the engine gets a few more hours. For example, 425F would not bother me climbing out if the engine will cool off in level flight with more air going through the engine.

Eventually you should be able to operate at cruise power conditions below 400F but even then, you might get hotter when climbing on a hot day.
 
One Flight

Hank Cheng ..

Are you allowed only one flight in the plane? What are the steps after first flight? And, what airport are you using? HKIA?
 
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